Toaster timing mechanism



A ril 15, 1952 Filed Jan. 5, 1947 F. w. SCHARF 2,592,826

TOASTER TIMING MECHANISM 2 SHEETS--SHEET l April 15, 1952 F. w. SCHARF2,592,826

TOASTER TIMING MECHANISM Filed Jan. 3. 1947 2=SHEETS--SHEET 2 PatentedApr. 15, 1952 UNITED STATES PATENT OFFICE TOAS'IER TIMING MECHANISMFrank W. Scharf, Arcadia, Calif., assignor, by

mesne assignments, to Knapp-Monarch Company, St. Louis, Mo., acorporation oi Delaware Application January 3, 1947, Serial No. 720,065

6 Claims. 1

My present invention relates to a toaster timing mechanism andparticularly one capable of producing successive slices of toast whichare substantially uniform in color.

One object of the invention is to provide a toaster timer having aheating element, and a bimetal element heated thereby, together withmeans to provide for quick recycling of the timer so there is no waitingbetween toasting operations. The timing means includes a heat transfershoe engageable with the heating element when the bimetal element snapsto off" position and engageable with a heat dissipator dur ing thetiming cycle.

Another object is to provide means for moving a heat transfer shoe insynchronism with latching and latch releasing mechanism of the timer.

Still another object is to provide timing mechanism in which a timingheater is rapidly cooled and a bimetal element heated thereby during thetiming period is spaced from the heater so that it can also coolrapidly, the bimetal element staying so spaced until a subsequenttoasting and timing cycle is initiated.

A further object is to provide a timer that is constructed and has sucha circuit arrangement as to compensate for general temperature rise ofthe toaster and produce substantially uniform toast.

With these and other objects in view, my invention consists in theconstruction, arrangement and combination of the various parts of mytimer whereby the objects contemplated are attained, as hereinafter morefully set forth, pointed out in my claims and illustrated in theaccompanying drawings, wherein:

Figure 1 is an end elevation of the toaster embodying my presentinvention.

Figure 2 is an enlarged vertical sectional view on the line 2--2 ofFigure 1 showing the timer in cold or inoperative position.

Figure 3 is a sectional view on the line 3-3.of Figure 2.

Figure 4 is a sectional view on the line 44 of Figure 2.

Figure 5 is a view similar to Figure 3 showing the timer adjusted forinitiating a timing cycle.

Figures 6 and 7 are sectional views on the lines G6 and 1-! of Figures 3and 5, respectively, and

Figure 8 is an electro-diagrammatic View of the circuits within thetoaster and its timing mechanism.

In the accompanying drawings, I have used the reference numeral 10 toindicate a toaster base and I! a housing for the toaster mechanism.Within the housing I: a pair of toasting compartments I4 are providedhaving the usual heating elements 16 shown diagrammatically in Figure 8and provided for the purpose of toasting bread inserted into thetoasting chambers 14. The usual bread carriers I! are provided, which inthe toaster illustrated, have an operating extension or arm l8 movablevertically with respect to the toasting chambers 14. The bread carriersare biased to move upwardly in the usual manner such as disclosed in mycopending application Serial No. 720,063, filed January 3, 1947, nowPatent No. 2,558,199, dated June 26, 1951.

For depressing the bread carriers [7, I provide a bread carrier lever 20pivoted thereto at 22' and terminating in an operating knob 24. Thelever extends through a slot 26 me housing [2. The lever 20 is normallyin the position shown by full lines in Figure 2 but when the knob 24 isdepressed the first movement is to the dotted position against the biasof a spring 21, which movement is permitted by a stop lug 28 and a slot30 on the bread carrier l8 and in the lever 20, respectively. The breadcarrier i8 is also provided with a, pin 32 which together with adownward extension 34 of the lever 20 cooperate with the timingmechanism as will be hereinafter described. Movement of the lever 20 tothe dotted position is limited by the extension 34 engaging a lug 35. v

Mounted on the base I0 is a bracket 36 forming a stationary frame for mytiming mechanism, which will now be described: A heater plate 38 ismounted stationary with respect to the bracket 36 by means of pins 40through ears 42 of the heater plate 38. The heater plate is channelshape in cross section as shown in Figures 6 and 7. and provided with apair of tubular. side edges 44 adapted to receive a. pair of heaters 46and 48. These are electrical timing heaters which when energizedtransmit heat to the heater plate 38 and such heat is conducted to abimetal timer strip in contact therewith as in Figure 7.

The top of the heater plate 38 is concave as shown in Figure 5 so thatthe bimetal 50 rests against it when bowed to the position shown, thebowing tendency being imparted to the bimetal element by means of aspring 52 connected with a. lever 54. The lever 54 has a V seat 56receiving one end of the bimetal element and its other end is receivedin a stationary V seat 58 secured to the frame 36. Due to thisconstruction, the bimetal element 50 may be sprung down as in Figure 5or up as in Figure 4. A cover 53 is provided for the spring 52. It willbe noted that the plate 38 is concave to fit the strip 50 when boweddown, the purpose being to secure good thermal con tact and thereforegood heat conduction.

Contacting at times with the lower surface of the heater plate 38 is aheat transfer shoe 5% shown in cross section in Figure 6. The shoe 69has flanges 62 which are adapted to contact at other times with a heatdissipator or radiator 54 as in Figure 7 (when the heat transfer shoe isin the lowered position). The shoe 60 acts to remove heat quickly fromthe heater plate 38 to prevent a second toasting cycle, though followingclosely a first cycle, from being unduly shorted due to the residualheat in the plate 38.

The shoe 60 is carried by an arm 66 pivoted to the center of the shoe asat 68, the arm 66 being pivoted to the frame 36 at '10. A spring I2normally constrains the lever 66 to rotate clockwise in Figure 3 to theposition shown, and the lever 66 is part of a latch lever 14 with whichacatch 16 engages as in Figure 5 to retain the levers 66 and 14 in acounterclockwise position as shown in this figure. A spring 18 tends torotate the catch 16 clockwise in Figures 3 and 5.

A catch release lever 80 is pivoted at 82 to the frame 35 and has a pin84 to engage a cam surface 86 of the catch 16. The catch release lever80 also-has an extension 88 adapted to contact or be contacted by thebimetal element 50 under certain circumstances and this extension isslotted as at 90 to oo-act with a screw 92 which serves to limit theupward and downward movement of the catch release lever.

A pair of stationary contacts 94 and 96 are mounted on the bracket 36and insulated from it.- A bridging contact'98 is carried by a sprin armI connected to the bread carrier arm Hi. The contacts are open inFigures 3 and 4, and are adapted to close as in Figure for establishingbread toasting and timing circuits.

Referring to Figure 8, the contact 96 is connected to a current supplyterminal I02 and the contact -94 is connected to the heater 46. Theheater 46 is also connected to the bread toasting heating elements 16,which in turn are connected to a second current supply terminal Hi4.Thus the heater 46 and the heating element I6 are in series with eachother and both are under control of the main switch 9496-98. Forchanging the timing period and thereby securingffcoior control for thetoast, the heater 45 may be shunted by a rheostat I06. A fixed resistor-108 is in series with the rheostat to prevent short circuiting theheater 46.

I have found that with only the heater; 45 there is a tendencyiorsuccessiv slices of toast to become lighter in color due toshortening of the timing period because of the general rise intemperature of the toaster. To compensate for this-tendency I providethe second heater 4 8 and a resistor H0. They shunt the heater 46 andthe heating elements I6 or are across the line.- The resistor H0 has ahighly positive co-efiicient of resistance. For instance, this resistormay be made of Hytemco wire. Accordingly, as the toaster temperaturerises, the resistance of the element H0 increases rapidly, therebycutting down the current flow through. the heater 48 and lengthening thetiming period with respect to its length if the heater 48 and theresistor H0 were not provided.

Practical operation In the operation of my disclosed toaster, when theparts are in the cold position of Figures 2, 3,

4 and 6, the bimetal element 50 is bowed upwardly. After the bread isplaced on the bread carrier, the knob 24 is depressed which swings theextension 34 of the lever to the dotted position of Figure 2 and inalignment with the upper edge of the latch releasing lever 80. Furtherdownward movement depresses the bread carrier arm l8 and causes theextension 34 to engage the catch release lever 80 and the pin 32 of thebread carrier arm to engage the upper edge of the latch lever 14.Further downward movement causes a hook 15 on the lever 14 to assume aposition over the pin 32 to hold the i bread carrier in lowered ortoasting position as in Figure 5. The latch lever 14 in turn is held bythe catch 16 which is moved by the spring 18 from the position of Figure3 to the position of Figure 5 after the left hand end of the latch lever14 passes the lower end of the catch I6.

During the downward movement of the catch releasing lever 80, itsextension 88 engages the bimetal element 50 and snaps it from theupwardly bowed position of Figure 3 to the down:- warclly bowed positionof Figure 5. Thelatch lever '14 through the lever 65 moves .thefhe'attransfer shoe to a position of contact with the heat dissipator 64.

Since the bridging contact 98 is now incone tact with the stationarycontacts 94 and 98,.the toasting and timing circuits are establishedandthe heaters 46 and 4B commence to heat up the heater shoe 38. At the endof the timing period as set by the knob 187 of the rheostat I96, thebimetal 50 snaps upwardly again to the position of Figure 3. In sodoing, it swings the catch release lever upwardly as shown by dottedlines in Figure 5 so that the pin 84 traveling along the cam surface 86will swing the catch 76 clockwise and release the latch lever '14. Thispermits the bread carriers IT to move upwardly under their spring biasas already described-by reason of the hook l5 permitting release of thepin. 32. The spring '12 of the latch lever M will swing the latch leverupwardly as soon as the catch 16 releases the latch lever and will alsoengage an extension at of the catch release lever to move this lever therest of the way upwardly to its initial position and out of the way ofthe bimetal element 50.

Upward movement of the latch lever 14 causes upward movement of the heattransfer shoe 60 as to the position of Figures 3, 4 and 6 so that thisshoe will absorb heat from the heater plate 38, thus conditioning it foran immediate -recycling of the timer as soon as other slices of breadcan be placed in the toaster with no wait:- ing necessary. When thetoaster is reset as in Figure 5, the shoe 60 then contacts-with the;heat dissipator 64 so that the heat can be quickly: carried away fromthe shoe 60. The bimetal 59 also remains spaced from the plate 38 tillreset, thus contributing to quick cool-down for; fast cycling.

The heat transfer shoe 60 is made of suitable metal, such as copper, andthe heat dissipator of aluminum or the like for quick heat absorptionand dissipation respectively to permit maximum efliciency in quickre-cycling of the toaster timing mechanism. The dissipator 54 may'have avertical portion 65 provided with ribs or flanges 61, to increase thetransmission of heat from the dissipator-to atmosphere.

The initial downward movement of the knob 24, as already stated, movesthe lever 34 into alignment with the latch lever 74- Upon releasing theknob 24, the lever 34 swings out again to the solid line position sothat it is out of the Way of the catch release lever 80 when it israised by the bimetal element 50.

In the event that it is desirable tomanually release the bread carrierbefore the end of th'e timing period, this is readily accomplished by asmall knob H2 on a lever I I4 pivoted to the plate 65 at H6. The innerend of the lever H4 is adapted to engage an extension 11 of the catch 16when the knob H2 is raised, thereby manually releasing the catch fromthe latch lever M'fas shown by dotted lines in Figure 5. Manual releaseof the bread carriers results in elevation of the bread and opening ofthe main switch 94--9698 without causing the bimetal element 50 to bowupwardly. As a result, the timing period is not upset and afterinspection of-the toast, the knob 24 can again be depressed-forcontinuing the same timing cycle withoutgvti'ie toast being off-color atthe end of the timing period. The bimetal element has the characteristicof normally staying in either bowed position and moves from thedownwardly bowed position to the upwardly bowed position only whenheated to a predetermined position by the heater plate 38. When a timingcycle is initiated, the bimetal is snapped from its upper position-toits lower position and remains there regardless of its temperature asthe toaster cannot be recycled quickly enough to result in reopenirigiofthe timer afterit is closed. Quick heat dissipation from both thebimetal element 50 and the shoe 60 eifect this desirable result.

Some changes'may be made in the construction and arrangement of theparts of my device without departing from the real spirit and purpose ofmy invention, and it is my intention to cover by my claimsany modifiedforms of structure or use of mechanical equivalents which may bereasonably included within their scope.

I claim as my invention:

1. In a timer mechanism, a timer including an electric heater and athermally responsive member, means to effect engagement between the twoupon initiation of a timing period, a heat transfer shoe engageable withsaid heater at the termination of the timing period, and a heatdissipator with which said shoe is engageable during the timing period.

2. A timer mechanism comprising a heater and a thermally responsivemember, means tojeifect engagement between the two upon initiation of atiming period, a heat transfer shoe engageable with said heater, meansto initiate a timing cycle, said means engaging said thermallyresponsive member with said heater, a catch to latchisaid means intiming position, said thermally responsive member being operable torelease said catch at the termination of the timing period, aifd a heatdissipator with which said means engages said heat transfer shoe duringthe timing period.

3. In a timer device of the character disclosed, an electrical heater,9. bowed bimetal element to be heated by engagement therewith and to bowaway therefrom when heated thereby to a predetermined temperature, alatch lever, a catch for said latch lever in position with said bimetalelement engaging said heater, means operable from said bimetal elementwhen heated to a predetermined degree for releasing said catch, and aheat transfer shoe spaced from said heater during the timing period andengageable with said heater upon release of said catch.

4. In a timer for an electrical appliance, a heater, a thermostatprimarily responsive to the heat generated by said heater for measuringand terminating the appliance cycle, means to modify the action of saidheater and thereby said thermostat in response to differences in theambient temperature of the device at the start of successive cyclescomprising a resistor in circuit with said heater and having a highlypositive temperature coeflicientiof resistance, and means to absorb theheat ofgthe heater when the thermostat is out of the circuit, said lastmeans including a heat radiator for dissipating the heat of said meanswhen the thermostat is in the circuit in order to render the thermostatoperable in cycles of rapid succession.

5. An electrical appliance, a timer thermostat responsive to heatgenerated during operation of the appliance for measuring andterminating a cycle of operation of the appliance, and means to absorbthe heatof the heater when said thermostat is in the open position, saidlast means including a heat" transfer shoe and a heat radiator fordissipating the heat absorbed by said shoe when the thermostat is in theclosed position.

6. In a timer'device, a thermostat, a heater therefor to operate thethermostat and thereby vcause it to open a circuit controlled thereby,and

REFERENCES CITED The following references are of record in the file ofthis patent:

UiirrED STATES PATENTS Number Name Date 2,196,393 Ireland Apr. 9, 19402,197,221 Koci Apr. 16, 1940 2,250,979 Winborne July 29, 1941 2,271,485Koci Jan. 27, 1942 2,302,117 Gomersall Nov. 17. 1942 2,422,199 Koci June17. 1947

